If you're a fan of the New Progressive trend you should know the Ozric Tentacles quite well. For those not "in the field" let me briefly explain which kind of Music the Ozric Tentacles create.
I hope you're familiar with the Seventies progressive rock musical genre (Gong, Yes, Genesis, E.L.P. etc.). If yes, add some space-age Music, noise samples, a mixture of synths and acoustic instruments, some deep influence from Asiatic music and you'll get close to the Ozric Tentacles technicolor musical universe!
Their Music is mostly instrumental, strongly rythmic, with electric bass, drums and ethnic percussions playing a key role among guitar and synth jammings.

Erpland is, perhaps, their most ambitious work, originally released on a double LP in 1990, then on CD by Dovetail (their own label) and finally (excellently) remastered by Snapper Music in 1998. The longish 12 tracks (for a total playing time of 73 minutes!) lead you into the middle of nowhere, drown by strongly hypnotic psychedelic musical patterns. I'd call "Erpland" a truly mystical experience, if I may.
Most of the tracks have been written by Ed Wynnie, guitarist extraordinaire and gifted synths player.

From a technical/audiophile point of view, this album is really interesting because of the weird mixture of fully-electronic sounds and acoustic instruments (flutes, tambourines, ethnic percussions...). The quality of the production (by Ed Wynnie himself) is very high and some tracks are highly demanding in terms of micro- and macro-dynamics.
The rythmic patterns are a mine field for any loudspeaker and amplifier, especially if you play the album LOUD, as it should be. "Toltec Spring", for example, opens up with a pleasant and relaxing "noise" of sheeps roaming across a pasture land. This bucolic pattern remains in the background while drums and percussions help to create the musical pattern for the entire track. As the track becomes more and more "intricate" one should still be able to distinctly detect the pastoral background noise. Since the percussion section is extremely powerful and energy demanding (attacks should be razor sharp here!!!) the speakers and the amplifier may be unable to follow the delicate background noise.
At the same time, the wide soundstage should never collapse, even at very high listening levels.
If you want an entertaining test for the ability of your system to keep up with the right musical tempo look no further than track 11 ("Inscence"). A reggae tempo with an extremely groovy and hypnotic electric bass pattern will shake the walls and make you stand up and dance. Play it as loud as you can: distortion levels are extremely low, so it's up to your system to not introduce distortion because of the high energy demand.
A good test for the dynamic capabilities of your system is also the first track "Eternal wheel", a special blend of space-age rock with highly distorted electric guitars and thumping bass lines.

Roughly speaking, the whole album is a "trip" into sound, a kaleidoscope of emotions and vibrations that your HiFi system MUST be able to reproduce with precision, harmonic richness and sheer energy. When one listens to the 3D atmosphere that this album can create, all the hype around multichannel becomes more and more ...nonsense.
A good 2-channel recording is all we need.

Conclusion

Ozric Tentacles are, among the progressive crowd, a real cult band. Their peculiar sound can be enjoyed by ANY Music lover, though. If you're after a good "trip" with your stereo system, do not miss this unusual progressive masterpiece.